Explosion-proof submergible electric motor and pump assembly



Dec. 6, 1955 A. ARUTUNOFF 2,725,824

EXPLOSION PROOF SUBMERGIBLE ELECTRIC MOTOR AND PUMP ASSEMBLY Filed Nov.24, 1954 2 Sheets-Sheet 1 INVENTOR ARMA/S ARU 7' U/VOF F ATTORNEY Dec.6, 1955 A. ARUTUNOFF 2,725,824

EXPLOSION PROOF SUBMERGIBLE ELECTRIC MOTOR AND PUMP ASSEMBLY ATTORNEYUnited States Patent EXPLOSION-PROOF SUBMERGIBLE ELECTRIC MOTOR AND PUMPASSEMBLY Armais Arutunoft, Bartlesville, 0kla., assignor to Reda PumpCompany, Bartlesville, Okla., a corporation of Delaware ApplicationNovember 24, 1954, Serial No. 470,850

I 8 Claims. (Cl. 103-87) This invention relates to electrically drivenpumps of the type embodying a centrifugal pump unit and an oil filledsubmergible electric motor unit superimposed coaxially thereon. Moreparticularly, the invention consists in new and useful improvements in acombined ressure equalizing and flame-propagation preventing unit foruse in connection with an oil filled submergible electric motor and pumpassembly.

Wherever multiple dispensers are required for delivery from a commonsupply source located below the ground, as for example in the case of agasolene storage tank at gasolene dispensing stations, it is desirableto employ submergible motor-pump units to push the gasolene or otherother volatile fluid of high vapor pressure up where ordinary suctiontype pumps are not efiicient or dependable. With this type of unit, themotor being located with the pump below the liquid level in the tank, itis advantageous to pump the fluid through a passageway surrounding theelectric motor and from thence to selected dispensing units. Thisarrangement facilitates the construction of a compact unit and aflords acooling medium for the electric motor augmenting the cooling eifect ofthe protecting and lubricating fluid with which the motor unit isfilled.

With submergible assemblies such as this, it is important to provide apressure equalizer to compensate for contraction and expansion of theinsulating and lubricating oil in the motor unit, resulting fromvariations in the pressure diflerential of the oil in the unit and thefluid surrounding the unit in the main tank. For this purpose it isknown to provide a collapsible element disposed in the oil filledreservoir and defining therein separate pressure zones, respectivelysubjected to the pressure existing in the reservoir and the tank. Thecollapsible element is sealed between the respective zones and isresponsive to variations in the pressure differentials above noted. Inthe interest of compactness and to avoid protruding electrical lines andconnections, it is desirable to carry the electrical conduits from themotor to the source of electrical energy above ground, through a cablehousing which extends axially through the reservoir and the collapsiblepressure equalizing element located therein. It therefore becomesimportant to take maximum precau tions against the propagation of flamein the event of a spark caused by a break in the insulation in thishousing and a rupture of the diaphragm or pressure responsive element,so as to prevent any spark from reaching the gasolene delivery line.

It is the primary object of the present invention to meet this need andprovide a combined equalizing and explosion preventing unit for use witha submergible assembly such as above referred to.

Another object of the invention is toprovide a fire propagationpreventing unit including a pair of minutely spaced concentric cylinderscommunicating at longitudinally spaced points with the area immediatelysurrounding the collapsible element and the annular fluid deliverypassageway, respectively thereby providing an annular clearance of largesurface area but minute cross section which will render it impossiblefor a spark or flame originating within the reservoir, to reach thegasolene delivery passageway.

A further object of the invention is to provide an extremely simpleconstruction and one which may be readily assembled and disassembledwith a minimum of elfort.

With the above and other objects in view which will appear as thedescription proceeds, the invention consists in the novel featuresherein set forth, illustrated in the accompanying drawings and moreparticularly pointed out in the appended claims.

Referring to the drawings in which numerals of like character designatesimilar parts throughout the several views.

Figures 1 and 1A collectively illustrate the complete submergibleassembly and show the relationship of the combined pressure equalizingand fire propagation pre venting unit.

Figure 2 is an enlarged longitudinal sectional view of the upper end ofthe assembly illustrating the combined equalizing and fire propagationpreventing unit, and

Figure 3 is a sectional view taken on line 33 of Figure 2.

In Figures 1 and 1A of the drawings I have shown the general assemblyembodying the invention, including a centrifugal pump unit 4, a motorunit 5 and the combined equalizing and explosion-proof unit 6,respectively, arranged in superimposed relation within a continuouscylindrical casing 7. The pump unit 4 is of the conventional centrifugaltype having a series of impeller stages (not shown) keyed to a centralshaft 8. As the particular structure of the centrifugal pump forms nopart of the present invention, they have not been illustrated but itwill be clearly understood from Figure 1A that the lower section 7a ofthe main casing 7 is closed by a bottom member 9, the. central portionof which is recessed as at 10 to provide an inlet valve body having avalve member 11, the stem 12 of which carries a coil surim is normallycausing the valve to seat in the valve body 10.

. An inlet port 14 in the bottom 9 places the interior of the casingsection 7a in communication with the interior of the tank (not shown)within which the assembly is submerged. A relief valve 15 may beprovided in the bottom 9 to relieve undue pressures Within the pumpunit.

The upper end of the pump unit 4 is closed by a transverse head 16,reduced and threaded at its lower extremity as at 17 to receive thethreaded upper end of the casing section 7a. The upper end of the head15 is also reduced and threaded as at 18 to receive the threaded lowerend of the main casing 7 which continues vertically and houses both themotor unit 5 and the equalizing and explosion-proof unit 6.

The details of the motor which may be conventional, are not shown, butas seen in the drawings, the motor is housedby a separate inner casing19 mounted on a reduced extension of the head 16 and inwardly spacedfrom the main casing 7 to provide an annular fluid delivery passageway20 which completely surrounds the motor and extends upwardly to theextremity of the easing 7, as will later appear. The discharge end ofthe pump unit 4 communicates with the annular passageway 20 throughfluid ports 21 provided in the lower portion of the head 16 and acentral opening in the head receives a bearing assembly 22 and shaftseal 23 for the combined pump and motor shaft 8.

A transverse partition 24 is annularly recessed at its lower side toreceive the upper extremity of the inner motor casing 19 and issimilarly recessed on its opposite side to receive the lower end of acasing section 19:: which forms a continuation of the casing 19 and,together with the adjacent portion of the outer casing 7, forms acontinuation of the annular passageway which ultimately discharges intoa discharge chamber formed at the upper end of the casing 7 by a closure26 which is recessed as at 27 to fit within the casing 7 to which it iswelded or otherwise secured.

The closure 26 is substantially frusto-conical in shape as shown inFigure 2, and its central portion is cut out and threaded as at 28 toreceive complementary external threads on a discharge conduit 29 leadingto the exterior of the main tank and from which the various supply linesdirect the fluid being dispensed, to selected dispensing units notshown.

The partition 24 terminates at its upper extremity in a centrallydisposed cylindrical neck 30, the bore 31 of which extends downwardlythrough the partition Where it is recessed as at 32 at its lower end toaccommodate a suitable bearing 33 for the upper extremity of thecombined pump and motor shaft 8. A series of converging radial openings34 in the partition 24 lead from the under side of the partition to theinterior of the bore 31, to receive the motor cables or conductors 35which extend from the motor unit 5 to a source of electrical energyabove ground (not shown), as seen in Figure 2.

The upper end of the neck terminates in a radially extended boss 36, thecentral portion of which is drilled as at 37 to form a restrictedextension of the bore 31. The opening 37 receives a sealing block 33 ofany suitable material and a washer 39, whereby the motor cables aresealed with respect to the upper end of the sleeve bore 31 from whichthey extend vertically through a housing conduit 40 secured to the boss36 by an adapter 41, later referred to more in detail.

The upper end of the inner casing section 19a is closed by an annularring guide 42 which is recessed to fit Within the upper end of thecasing section and is held in place by a lock nut 43, internallythreaded as at 44 to engage complementary threads on the projectingportion of the boss 36. Thus, there is formed within the casing section1%, an annular reservoir or protecting chamber 45, surrounding the neck30 and bounded at its upper and lower ends by the ring guide 42 andpartition 24, respectively.

Within the chamber 45 and concentric with the neck 38, i provide acollapsible cylinder or breathing member 46 which is secured at itsopposite ends to the boss 36 and a reduced shoulder on the partition 24.Any suitable means may be employed for connecting the ends of thecylinder 46 to the boss and partition, such for example, as linen threador the like 47 which will afford a sealed connection. Inasmuch as thecylinder 46 is subjected to contact with the lubricating and protectingfluid of the motor as well as the gasolene being dispensed, as willlater appear, it must be composed of a flexible material which is notvulnerable to chemical attack by either of these fluids. Variousmaterials are adaptable for this purpose such as Buna-N and neoprenewhich have the desirable properties of flexibility and will withstandchemical attack.

Thus, within the chamber 45, the collapsible cylinder 46 provides anouter annular zone 48 and an inner annular zone 49, both surrounding theupstanding neck 30. The inner zone 49 communicates with the bore 31 inthe neck 3% through radial ports 50 at the upper end of the neckadjacent the boss 36 and the boss is provided with filling openings 51and 52 by means of which the inner zone or compartment 48 may be filledwith lubricating and protecting fluid, said filling openings beingclosed by any suitable plugs 53. Thus, by removing both plugs 53 andusing one opening as a filling opening and the other as a vent,lubricating and protecting fluid introduced into the compartment 49,fills the area surrounding the neck 31 and overflows into the bore 31through ports 50 until the entire motor unit 5 is filled with fluid,whereupon the plugs 53 are replaced.

A cylindrical bathe sleeve 54 of relatively thin metal is arranged inminutely spaced relation with respect to the inner periphery of theinner casing section 19a to provide an annular space 55 of large surfacearea but restricted cross section which completely surrounds the outercompartment or zone 48. In Fig. 2 the lateral spacing of the sleeve 54with respect to the casing section 19a is exaggerated for purposes ofillustration.

The lower portion of the outer compartment 48 communicates with theminute space 55 through radial ports 56 and the upper portion of thespace 55 in turn, communicates with the gasolene delivery passageway 20surrounding the casing section 19a, by means of radial ports 57. Thus,the outer compartment 48 is subjected to the pressure conditionsprevailing in the gasolene tank and delivery line 20 through thecommunicating ports 56 and 57 while the inner compartment 43, separatedfrom the outer compartment 48 by the collapsible cylinder 46, issubjected to the pressure conditions prevailing within the motor,through the bore 31 in neck 30 and the communicating ports 50.

Spacer rings 58 support the opposite ends of the thin sleeve 54 andmaintain the desired spacing to define the proper cross-sectionaldimension of the annular space 55.

The proper spacing of the upper end of the casing section 19:: withrespect to the main outer casing 7, is maintained by radially projectinglugs 59 extending from the ring guide 42. Preferably, the adapter 41 isprovided with flanges 60 projecting in opposite directions and drilledto receive retaining screws 61 by means of which the adapter is rigidlysecured to the boss 36 as shown in Fig. 3. A reduced extension 62 on thelower end of the adapter 41 fits within the opening 37 in the boss andserves to retain the cable seal 38 in sealing engagement within itsopening.

The entire assembly is submerged in a gasolene or other fluid supplytank below ground, the motor unit first having been filled withlubricating and protecting fluid as previously described. Upon operationof the electric motor the lubricating and protecting fluid naturallyexpands to some extent due to the heat of the motor and as the volume ofliquid in the motor and the inner compartment 49 increases, the flexiblecylinder 46 expands to the necessary extent, correspondingly reducingthe volume of the gasolene or other dispensed fluid in the outercompartment 43 by forcing the latter outwardly through ports 56 and 57with the intervening annular space 55. When the motor is stopped theliquid contracts and reduces in volume, whereupon the flexible cylinder46 is collapsed upon the entrance of gasolene from the deliverypassageway 20 into the outer compartment 48. When the motor starts againthe expansion of the protecting liquid simply expands the cylinder 46and forces the gasolene which has entered the outer compartment 48, backthrough the ports 56 and 57 and the passageway 55.

Should a spark occur as a result of a break in the insulation of thecable 35 for example, and the diaphragm or collapsible cylinder 46 beruptured, it would be impossible for any spark or flame to reach thegasolene delivery passageway 20 or delivery conduit 29 as such flamewould be extinguished in the outer compartment 48 due to the smallannular clearance between the sleeve 54 and the casing section 19a andthe distance of travel necessary between the ports 56 in the sleeve 54and the ports 57 at the outer end of the casing section 19a.

It will thus be seen that with this improved assembly the motor iscompletely isolated from the gasolene being dispensed and variations inpressure caused by expansion and contraction of the motor protectingfluid, is prevented from diluting the protecting fluid by the entranceof gasolene into the motor unit. Furthermore, the assembly is renderedcompletely explosion proof by the arrangement of the sleeve 54 inminutely spaced relation from the casing section 19a, formingtherebetween a restricted space of great length and great coolingcapacity.

Compactness and ease of asembly is another feature of importance. Forexample, it will be noted that a single nut 43 on the boss 36 at theupper end of the neck 30, retains the entire protecting and explosionproof unit in assembled relation.

From the foregoing it is believed that the invention may be readilyunderstood by those skilled in the art without further description, itbeing borne in mind that numerous changes may be made in the details ofconstruction without departing from the spirit of the invention as setforth in the following claims.

What I claim is:

1. A submergible electric motor and pump assembly comprising a pumpunit, an oil filled electric motor unit superimposed concentricallythereon, a lubricating and protecting fluid reservoir above said motorunit, an outer casing enclosing said units and reservoir, a fluiddelivery conduit connected concentrically to the upper end of said outercasing, an inner casing housing said motor unit and extending upwardlytherefrom to form the annular boundary wall of said reservoir, saidinner casing being spaced from said outer casing to form therewith anannular fluid delivery passageway encircling said motor unit andreservoir, with its upper end communicating with said fluid deliveryconduit, discharge ports in said pump unit leading to said passageway, atransverse partition above said motor unit, defining the bottom of saidreservoir, a head closing the upper end of said reservoir, a cylindricalmembrane of flexible material dividing said reservoir into concentricinner and outer compartments, the inner compartment communicating withsaid oil filled motor unit, ports at the upper end of said extendedinner casing, placing said outer compartment in communication with saidfluid delivery passageway, whereby said membrane is responsive to thedifferential pressures of the motor unit and delivery passageway, firepropagation preventing means comprising a thin metal baflie sleeve insaid outer compartment in closely spaced relation to said inner casing,forming therewith an intervening passageway of large surface area andminute cross-section, and ports at the lower end of said sleeve placingthe outer compartment in communication with said intervening passagewayand through the ports in said extended inner casing, with said deliverypassageway.

2. A submergible electric motor and pump assembly comprising a pumpunit, an oil fllled electric motor unit superimposed concentricallythereon, a lubricating and protecting fluid reservoir above said motorunit, an outer casing enclosing said units and reservoir, a fluiddelivery conduit connected concentrically to the upper end of said outercasing, an inner casing housing said motor unit and extending upwardlytherefrom to form the annular boundary wall of said reservoir, saidinner casing being spaced from said outer casing to form therewith anannular fluid delivery passageway encircling said motor unit andreservoir, with its upper end communicating with said fluid deliveryconduit, discharge ports in said pump unit leading to said passageway, atransverse partition above said motor unit, defining the bottom of saidreservoir, a head closing the upper end of said reservoir, a tubularneck extending concentrically between said partition and bottom to formthe inner wall to said reservoir, said head and bottom having openingsto the bore of said neck to accommodate the lead wires from said motorunit, a gland sealing said bore around said lead wires, a cylindricalmembrane of flexible material dividing said reservoir into concentricinner and outer compartments, ports in said neck placing the innercompartment in communication with said oil filled motor unit, ports atthe upper end of said extended inner casing, placing said outercompartment communicating with said fluid delivery passageway, wherebysaid membrane is responsive to the differential pressures of the motorunit and delivery passageway, fire propagation preventing meanscomprising a thin metal baflle sleeve in said outer compartment inclosely spaced relation to the inner casing, forming therewith anintervening passageway of large surface area and minute cross section,and ports at the lower end of said sleeve placing the outer compartmentin communication with said intervening passageway and through the portsin said extended inner casing, with said delivery passageway.

3. A fire propagation preventing device for oil filled submergibleelectric motor and pump assemblies of the type wherein the motor unit isconcentrically superimposed on the pump unit and surmounted by a fluidreservoir, with a continuous outer casing housing said units andreservoir, and including an inner casing enclosing said motor unit andreservoir and spaced from the outer casing to form an annular fluiddelivery passageway surrounding said motor unit and reservoir Withinsaid outer casing; said device comprising a thin metal baflle sleeve insaid reservoir in closely spaced relation to said inner casing, formingtherewith an intervening passageway of large surface area and minutecross section, whereby any communication between said reservoir andfluid delivery passageway is prevented, except through said restrictedannular passageway.

4. Apparatus as claimed in claim 3, including a flexible cylindricalmembrane dividing said reservoir into inner and outer compartments,means placing the inner compartment in communication with said oilfilled electric motor, and staggered ports in said baflie sleeve andinner casing, respectively, placing said outer compartment incommunication with said fluid delivery passageway through saidrestricted passageway.

5. A combined equalizing and fire propagation preventing unit for oilfilled submergible electric motor and pump asemblies, housed in acontinuous cylindrical outer casing, including an inner casingconcentric with said outer casing and spaced inwardly therefrom to forman annular fluid delivery passageway leading from the discharge of saidpump, a transverse partition in said inner casing forming the bottom ofa fluid reservoir located above said motor and in communicationtherewith, a flexible cylindrical membrane dividing said reservoir intoinner and outer compartments, said inner compartment communicating withsaid motor unit, ports in the upper end of said inner casing placingsaid outer compartment in communication with said annular fluid deliverypassageway, a thin metal baflie sleeve in said outer compartment inclosely spaced relation to said inner casing, forming therewith anintervening passageway of large surface area and minute cross section,and ports at the lower end of said sleeve placing the outer compartmentin communication with said intervening passageway and through the portsin said inner casing, with said delivery passageway.

6. A combined pressure equalizing and fire propagation preventing devicefor submergible electrically driven motor and pump assemblies of thetype including an outer casing having a pump unit at the lower end, asuperimposed motor unit concentric with said pump unit, an inner casinghousing said motor and spaced from said outer casing to form therewithan annular fluid delivery passageway leading from said pump around saidmotor, said device comprising a lubricating and protecting fluidreservoir formed by said inner casing, in said motor unit above saidmotor, a transverse partition defining the bottom of said reservoir, anupstanding tubular sleeve formed concentrically on said partition,defining the inner wall of said reservoir, the bore of said sleeve beingopen to said motor to receive the lead wires from the latter, a port insaid neck to permit the passage of fluid from the reservoir to themotor, a gland sealing said lead wires in said bore, the upper end ofsaid neck having a radically enlarged boss threaded at its extremity, aclosure for the top of said reservoir, having a central opening toreceive the projecting threaded end of said boss, a closure retainingnut for said threaded boss, a flexible cylindrical membrane securedbetween said boss and partition,

dividing said reservoir into concentric inner and outer compartments,the inner compartment communicating with said motor through said neck,ports in the upper end of said inner casing, placing the outercompartment in communication with said delivery passageway, a firepropagation preventing sleeve of thin metal in said outer compartment,in closely spaced relation to said inner casing, forming therewith anintervening passageway of large surface area and minute cross section,and ports at the lower end of said sleeve placing the outer compartmentin communication with said intervening passageway and through the portsin said inner casing, with said delivery passageway.

7. A device as claimed in claim 6, including a spacing ring at oppositeextremities of said sleeve, said closure adapted to abut the uppermostring, whereby when said retaining nut is tightened, said sleeve andrings are maintained in fixed position.

8. An oil filled submergible electric motor and pump assembly comprisinga pump unit, a motor unit arranged concentrically above said pump unitand having a motor shaft operatively connected to said pump, lead wiresfor said motor unit, a combined pressure equalizing and flamepropagation preventing unit arranged concentrically above said motorunit, a continuous cylindrical shell housing said units, an inwardlyspaced concentric casing housing said motor unit and protecting unit andforming with said shell, an annular fluid delivery passageway, atransverse partition at the lower end of said casing, separating themotor unit from the pump unit, ports connecting the discharge end ofsaid pump unit to said fluid delivery passageway, a second transversepartition in said casing defining therein a protecting fluid reservoirabove said motor unit, means providing fluid communication between saidmotor unit and said reservoir, said second partition having a concentricupstanding tubular neck for receiving the lead wires from said motorunit, a concentric fluid discharge conduit connected to the upper end ofsaid shell and leading from said annular passageway, a tube within saidconduit, concentric with said neck for housing said lead wires, a glandsealing said lead wires in said neck, an annular head closing the upperend of said reservoir, collapsible cylindrical membrane extendingbetween said head and second partition in spaced relation to said neck,to form in said reservoir inner and outer concentric fluid compartments,ports in said neck, the inner compartment encircling said neck andcommunicating with said motor unit through the ports in said neck, athin metal baffle sleeve interposed in said outer compartment betweensaid cylindrical membrane and said casing, in closely spaced relation tothe latter, forming therewith an intervening annular passageway of largesurface area and minute cross section, ports at the lower end of saidsleeve placing said outer compartment in communication with saidintervening passageway, and ports at the upper end of said casing,placing said lastnamed passage way in communication with said fluiddelivery passageway.

References Cited in the file of this patent UNITED STATES PATENTS2,319,934 Korte et al. May 25, 1943 2,423,436 Blom July 8, 19472,674,194 Arutunotf Apr. 6, 1954

